Like automobiles, the basic principles of most sewing machines are the same. The core of the car is the internal combustion engine, and the core of the sewing machine is the coil suture system.
There is a great difference between the suture method and the ordinary manual sewing. In the simplest manual stitching, the sewing machine is attached to a line in the small eye at the end of the needle, and then the thread is completely crossed through two pieces of fabric, from one side to the other, and then back to the original side. In this way, the needle leads the line in and out of the fabric, stitching them together.
Although this is very simple for the manual, it is extremely difficult to pull with the machine. The machine needs to release the needle on one side of the fabric and then grab it on the other side immediately. Then it needs to pull all the loose lines out of the fabric, turn the needle in the direction, and repeat all the steps in the opposite direction. This process is too complex and impractical for a simple machine, and it works only with shorter lines, even for manual purposes.
Instead, the sewing machine simply passes the needle part through the fabric. On the machine, the needle is at the back of the tip, not at the end of the needle.
The needle is fixed on the needle rod, and the pin is driven up and down by the motor through a series of gears and cams (described in detail later).
When the tip of the needle passes through the fabric, it pulls a small coil on the other side. A device underneath the fabric will grab the coil and wrap it around another wire or another coil of the same thread. In the next two sections, we'll see how the system works.
The simplest stitch stitching is chain stitch. To sew a chain stitch, the sewing machine will be at the back of the line with the same length of wire ring. The fabric is located on a sheet of metal underneath the needle and is fixed with a presser foot. Each stitch begins with the needle pulling through the fabric to pull out a coil. A device that makes a coil catches the coil before the needle is pulled, and the device moves synchronously with the needle. Once the needle is pulled out of the fabric, the Bougat device (described later) pulls the fabric forward.
When the needle passes through the fabric again, the new coil will go straight through the middle of the previous coil. The device that makes the coil will hold the line again and coil around the next coil. In this way, each coil will hold the next coil in place.
The main advantage of chain stitching is that it can be sewn very quickly. However, it is not particularly strong and if one end of the line is loosened, the whole sewing may be loose. Most sewing machines use a more robust suture, called a lock seam. You can find out how a typical locking device works in the following animation.
The most important component of the sewing device is the pendulum hook and the spool assembly. A spool is a coil of yarn that is placed underneath the fabric. It is located in the center of the pendulum, which rotates under the drive of the motor and synchronizes with the motion of the needle.
Like a chain stitch, the needle pulls a coil through the fabric, it rises again while the cloth is moving forward, and then the other line is trapped into it. The suture mechanism, however, is not to connect the different coils together, but to connect them with another section of the thread that is released from the spool.
When the needle sets the line into the coil, rotate the pendulum to catch the coil with a crochet hook. As the pendulum rotates, it pulls the line around the thread from the spool. This makes the stitching very strong.
This kind of spinning spindle is also evolved through the direct spindle.
The coil suture principle of sewing machine is evolved from the direct spindle to the spinning spindle, and it enters the mature stage.